i^.  K  S.  LiB-RARY.  Cop-  a»  .  C.  «^  <=< 

THE  CONNECTICUT 

AGRICUITDRAL  EXPERIMENT  SIMIOE 

NE^W     HAVEN,     CONN. 


BULLETIN   166,  NOVEMBER,    1910. 


THE  MANAGEMENT  OF  TOBACCO 
SEED  BEDS. 

V 

By  W.  M.  HiNSON  and  E.   H.   Jenkins. 


The  Bulletins  of  this  Station  are  mailed  free  to  citizens  of  Con- 
necticut who  apply  for  them,  and  to  others  as  far  as  the  limited 
editions  permit. 


CONNECTICUT    AGRICULTURAL   EIPERIIENT    STATION. 


BOARD   OF   CONTROL. 
His  Excellency,  Frank  B.  Weeks,  Ex  officio,  President. 

Prof.  H.  W.  Conn,  Vice  President Middletown. 

,  Secretary  

E.  H.  Jenkins,  Director  and  Treasurer New  Haven. 

George  A.   Hopson Wallingford. 

Charles   M.  Jarvis Berlin. 

Frank  H.   Stadtmueller Elmwood. 

James  H.  Webb Hamden. 


STATION    STAFF. 

Chemists. 

Analytical  Laboratory. 

John  Phillips  Street,  M.S.,  Chemist  in  Charge. 

E.  Monroe  Bailey,  M.S.  C.  B.  Morrison,  B.S. 

R.  B.  Roe,  A.B.     .  C.  E.  Shepard. 

Laboratory  for  the  Study  of  Proteids. 
T.  B.  Osborne,  Ph.D.,  Chemist  in  Charge.    E.  L.  Ferry,  Assistant. 
Botanist,  G.  P.  Clinton,  S.D.    Assistant,  E.  M.  Stoddard. 
Entomologist,  W.  E.  Britton,  Ph.D.    Assistant,  B.  H.  Walden. 
Forester,  Samuel  N.  Spring,  M.F.    Assistant,  W.  O.  Filley. 
Plant  Breeding,  H.  K.  Hayes,  B.Agr. 
Seed  Testing,  Miss  M.  H.  Jagger. 

Stenographers  and  Clerks.    Miss  V.  E.  Cole,  Miss  L.  M.  Brautlecht, 

Miss  E.  B.  Whittlesey,  Miss  Luva  Francis. 
In  Charge  of  Buildings  and  Grounds,  William  Veitch. 
Laboratory  Helper,  Hugo  Lange.    Sampling  Agent,  V.  L.  Churchill. 


THE  MANAGEMENT  OF  TOBACCO 
SEED  BEDS. 

By  W.  M.  Hinson  and  E.  H.  Jenkins. 

This  bulletin  is  a  part  of  the  cooperative  experimental  work  done  jointly 
by  the  Bureau  of  Plant  Industry  of  the  United  States  Department  of 
Agriculture,  represented  by  Mr.  Hinson,  and  by  this  Station. 

The  object  of  the  seed  bed  is  to  get  healthy  stocky  plants  with 
compact  roots  ready  to  set  in  the  field  when  the  ground  and  air 
are  warm  enough  for  them  to  grow  rapidly  and  without  check. 
This  bulletin  aims  to  give  what  experiment  and  observation  have 
taught  regarding  this  matter. 

The  same  beds  may  be  used  for  years  if  properly  handled, 
and  this  plan  makes  it  worth  while  to  build  substantial  wooden 
frames,  to  hold  the  cloth  or  sash  and  in  some  cases  to  lay  steam 
or  water  pipes  in  the  bed  for  heating  in  emergency.  The 
dangers  from  the  accumulation  of  weeds,  the  increase  of  fungi 
or  "disease"  in  the  soil,  and  the  sprouting  of  tobacco  seed  pos- 
sibly of  a  different  variety  sowed  the  previous  year,  are  all 
obviated  by  the  sterilization  of  the  bed  with  steam,  to  be 
described  later. 

Fertilisers.  Tobacco  plants  of  the  right  size  to  set  in  the  field 
carry  very  little  plant  food  in  them  and  can  grow  to  the  proper 
size  for  transplanting  in  a  poor  soil.  But  if  they  grow  in  either 
a  poor  or  a  dry  soil,  they  have  to  spread  their  roots  widely 
in  it  in  order  to  get  the  food  or  water  which  they  need.  This 
delays  their  growth  above  ground,  the  spreading,  straggling 
roots  are  damaged  in  transplanting  and  the  plant,  as  a  result, 
is  checked  in  growth. 

But  in  a  well-fertilized  bed  the  roots,  finding  all  the  plant  food 
and  water  which  they  need  close  at  hand,  make  a  compact  bunch 
of  roots  easy  to  pull  with  slight  loss  to  the  seedling  plant.  To 
secure  this  it  is  not  necessary  to  use  exceptionally  large  doses  of 
fertilizer. 


4  CONNECTICUT   EXPERIMENT   STATION,    BULLETIN    l66. 

The  complete  or  partial  failure  of  beds  is  oftener  caused  by 
too  thick  seeding  and  want  of  skill  or  care  in  watering  and  partic- 
ularly in  airing  the  beds  than  by  over-fertilizing  or  under- 
fertilizing  the  soil.  If  the  plants  do  not  grow  as  they  ought, 
seek  the  cause  in  these  things  and  in  diseases  which  result  from 
insufficient  ventilation  before  dosing  the  bed  with  fertilizers. 

Horse  manure  is  an  excellent  dressing,  for,  aside  from  its 
fertilizing  value,  the  vegetable  matter  in  it  makes  the  soil  hold 
and  carry  water  better  than  it  could  without  it  and  feeds 
the  bacteria  which  make  nitrogenous  manures  available.  If  beds 
are  steam-sterilized,  the  weed  seeds,  which  are  always  present 
in  manure,  will  give  no  trouble. 

Usually  it  is  best  to  prepare  the  beds  and  work  in  manure  in 
the  late  fall,  thus  leaving  less  to  be  done  in  the  rush  of  spring 
work.  A  thick  cover  of  leaves  on  the  bed  prevents  deep  freez- 
ing and  makes  the  beds  workable  somewhat  earlier  in  the  spring. 

A  moderate  amount  of  chemical  fertilizers  should  be  put  on 
in  spring,  worked  in  with  the  rake,  and  the  bed  cleaned  of  all 
trash  and  smoothed  ready  for  seeding. 

Object  of  Sterilizing  the  Beds.  To  this  matter  we  wish  to 
call  special  attention.  The  sterilization  of  beds  used  for  forcing 
greenhouse  crops  has  been  practiced  by  successful  growers  for 
years.  The  results  of  our  experiments  in  sterilizing  tobacco  beds 
have  led  some  successful  growers  to  adopt  this  practice,  which 
has  thus  been  abundantly  tested  and  has  proved  to  be  practicable 
and  profitable.  The  practice,  which  will  be  described  in  detail 
later,  consists  either  in  steaming  the  soil  sufficiently  to  kill  all 
seeds  and  microbes  in  it  to  the  depth  of  two  inches  or  more,  or 
in  treating  the  beds  with  formalin  to  largely  accomplish  the  same 
thing.  Beds  which  have  been  properly  sterilized  by  steam  will 
need  no  weeding,  as  only  an  occasional  weed  will  show  itself 
before  the  seedling  tobacco  plants  are  pulled.  This  saving  of 
labor  alone  pays  the  cost  of  sterilizing  when  the  apparatus  for  it 
is  at  hand.  The  root  rot  will  also  be  killed  and  the  tobacco  thus 
saved  from  its  attacks.  Whether  "calico"  is  lessened  by  the 
treatment  has  not  been  determined,  although  our  observation 
this  year,  to  which  we  refer  later,  suggested  that  this  might  be 
the  case. 


STERILIZATION  OF  BEDS.  5 

It  is  a  matter  of  common  observation,  both  in  greenhouses  and 
in  tobacco  beds,  that  the  plants  in  steriHzed  soil  start  quicker 
and  grow  faster  than  in  untreated  soil.  This  may  be  in  part 
explained  by  the  warming  of  the  soil,  partly  by  a  possible  solvent 
action  of  the  steam  or  heated  moisture  on  the  plant  food  in  the 
soil,  but  is  no  doubt  in  large  part  due  to  a  change  in  the  microbe 
life  of  the  soil  effected  by  the  treatment,  which  may  utterly 
destroy  certain  kinds  of  microbes,  repress  others  and  yet  leave 
conditions  favorable  for  the  rapid  growth  later  of  those  species 
which  make  available  the  nitrogen  of  the  soil  or  otherwise  favor 
the  growth  of  the  tobacco  plant. 

The  root  rot  and  some  other  fungous  troubles  appear  to  be 
completely  destroyed  by  steam  sterilization  and  largely  by  the 
formalin  treatment. 

Apparatus  for  Steam  Sterilizing.  There  are  required  a  port- 
able steam  boiler — six  to  eight  horse  power — which  will  maintain 
a  pressure  of  from  75  to  100  pounds,  and  steam  hose  which  will 
stand  that  pressure,  with  the  necessary  connections.  The  steam- 
ing apparatus  found  most  convenient  was  devised  by  Mr.  A.  D. 
Shamel  and  is  shown  in  the  plate. 

It  is  a  pan  six  by  ten  feet  square  and  six  inches  deep,  made 
of  i8-gauge  galvanized  iron  and  having  a  handle  bar  at  each  end. 
It  is  reinforced  with  strap  iron  to  make  it  more  rigid  and  is  fitted 
with  a  nipple  for  the  hose  connection.  The  one  in  use  at  East 
Hartford  cost  $40.00  and  should  last  ten  years. 

If  a  sterilizing  pan  cannot  be  got  readily,  experience  has  shown 
that  a  tight  wooden  box  of  about  the  same  measurement  is  equally 
effective  and  being  a  poor  conductor  of  heat  probably  needs  less 
steam  to  do  the  same  work. 

The  Operation  of  Steam  Sterilizing.  The  bed,  having  been 
fertilized,  is  raked  smooth  and  made  ready  for  sowing.  The 
pan  is  inverted  over  one  end  of  the  bed  and  its  edges  pressed  well 
into  the  soil.  Steam  is  turned  on  and  kept  at  a  pressure  of  at 
least  70  pounds  for  thirty  minutes.  Some  experimenters  recom- 
mend an  hour,  but  in  our  work  this  year  thirty  minutes  was 
sufficient  to  kill  all  seeds. 

The  pan  is  then  moved  on,  and  it  is  recommended  to  cover 
the  steamed  soil  with  burlap  to  hold  the  heat  as  long  as  may  be. 


6  CONNECTICUT    EXPERIMENT   STATION,    BULLETIN    l66. 

Where  the  beds  are  many  and  long,  much  time  can  be  saved 
by  putting  the  boiler  midway  of  the  bed  and  using  two  sterilizers, 
one  at  each  end  of  the  bed.  The  steam  is  turned  into  the  second 
when  the  first  has  been  steamed  for  thirty  minutes,  and  the  pan 
remains  there  to  hold  the  heat  for  twenty-five  minutes  and  is 
then  moved  on. 

To  sterilize  i8o  square  yards  of  seed  beds  this  year  at  W.  K. 
Ackley's  in  East  Hartford  cost  the  labor  of  two  men  for  two 
days,  $6.00.     No  weeding  was  needed  on  these  beds. 

To  weed  90  square  yards  of  unsterilized  beds  till  the  seedlings 
were  pulled,  cost  in  labor  $12.00. 

The  beds  were  sterilized  April  nth  and  12th.  Seed  was  sown 
on  the  15th.  The  covers  were  taken  off  the  beds  May  15th  and 
the  seedlings  were  ready  to  set  on  June  2d,  all  of  them  healthy. 

The  plants  on  unsterilized  and  hand-watered  beds  were  one 
week  later. 

As  to  the  effect  on  prevalence  of  "calico,"  we  do  not  yet  attach 
great  importance  to  our  observations  because  of  the  freaky  way 
in  which  this  trouble  appears.  Part  of  the  field  was  set  with 
plants  from  the  sterilized  bed  and  part  from  an  adjoining  one 
which  was  not  sterilized.  We  counted  all  the  plants  in  two  rows 
on  both  parts  and  also  the  number  of  "mongrels"  or  "calico" 
plants.  Only  2.V1  per  cent,  of  the  plants  from  sterilized  beds 
showed  the  trouble,  but  from  the  unsterilized  bed  30  per  cent. 
But  on  a  neighbor's  field,  where  the  same  experiment  was  made, 
the  difference  was  not  great,  though  still  quite  evidently  in  favor 
of  the  plants  from  sterilized  soil. 

The  subject  of  "calico"  is  further  discussed  in  the  last  para- 
graph of  this  bulletin. 

Sterilisation  with  Formalin  or  Formaldehyde.  Steam  steril- 
ization is  the  more  convenient  where  a  boiler  is  near  at  hand  and 
effective  in  killing  weed  seeds,  but  for  small  beds  and  places 
where  the  other  apparatus  cannot  be  got,  the  formalin  treatment 
can  be  substituted.  It  is  best  applied  in  the  fall  and  when  the 
soil  is  comparatively  dry.  The  following  method  was  success- 
fully used  by  Dr.  Clinton  of  this  Station  in  1907 : 

A  solution  of  one  part  of  formalin — 40  per  cent,  strength, — 
in  one  hundred  parts  of  water,  that  is,  a  pint  of  good  commercial 
formaldehyde,  also  called  "formalin,"  in  twelve  and  one-half 
gallons  of  water,  was  gradually  sprinkled  over  the  bed  at  the 


RATE  OF  SEEDING.  7 

rate  of  one  gallon  per  square  foot,  taking  care  not  to  puddle  the 
soil.  The  bed -was  then  covered  with  burlap  or  sash  to  hold  in 
the  fumes. 

Spring  treatment  leaves  the  bed  wet  and  cold  and  it  should 
not  be  sown  for  a  week  after  treatment,  lest  the  formalin  still 
in  the  soil  should  kill  the  sprouting  seed.  Stirring  the  soil  will 
facilitate  the  evaporation  of  the  formalin  and  excessive  moisture. 

Rate  of  Seeding.  Assuming  that  clean  heavy  seed  is  used,*  we 
wish  to  call  attention  to  the  rate  of  seeding.  The  practice  of 
different  good  growers  varies  greatly.  Four  successful  growers, 
each  raising  a  large  acreage,  gave  us  their  rates  of  seeding  which, 
calculated  to  a  common  basis,  are  respectively : 

I  tablespoonful,  or  i  oz.  to  150  sq.  feet. 

I  "  "I    "     "   450    "      " 

Now  one  ounce  of  seed  contains  approximately  300,000  seeds, 
of  which,  assuming  a  germination  of  only  75  per  cent.,  225,000 
will  sprout  and  grow. 


5 
plants 

3 
plants 

1 

less  than 

3 
plants 


Let  the  reader  imagine  the  number  of  seedling  plants  given 
above  standing  in  the  inch  squares  and  he  will  see  exactly  what 
the  above  figures  mean  and  understand  how  thickly  the  plants 
will  stand  on  each  square  inch  of  his  beds,  providing  75  per  cent, 
of  his  seed  "comes." 

With  ten  seedlings  on  a  square  inch,  or  even  half  that  number, 
it  is  clear  that  large  numbers  must  die  from  lack  of  light,  damp- 

*The  advantage  of  heavy  seed  and  the  method  of  separating  chaff  and 
light  seed  from  it  have  been  explained  in  the  Report  of  this  Station,  1905, 
P-  334)  and  in  Bull.  96  of  the  Bureau  of  Plant  Industry. 


8  CONNECTICUT    EXPERIMENT    STATION^    BULLETIN    l66. 

ing  off,  etc.,  or  remain  stunted,  at  least  till  the  overtopping  ones 
are  pulled.  Such  thick  crowding,  we  believe,  weakens  all  the 
plants,  makes  them  spindling  and  very  hard  to  pull  properly  for 
setting  in  the  field. 

An  ounce  of  dry  seed  is  enough  to  sow  on  900  square  feet  of 
bed,  and  this  will  give  a  stand  of  not  more  than  two  plants  to 
the  square  inch. 

Sprouted  or  Dry  Seed?  It  is  a  very  common  practice  to  mix 
the  seed  with  damp  apple-tree  "punk,"  or  other  suitable  material, 
and  leave  it  in  a  jar  in  a  warm  place  until  the  seed  has  "cracked" 
and  the  sprout  appears  and  then  sow  the  mixture.  If  a  hard,  cold 
storm  comes  at  the  time,  the  grower  naturally  waits  for  a  better 
day.  Then  the  sprouts  have  grown  too  long  and  are  likely  to 
be  broken  in  sowing,  or  if  not  broken  they  must  twist  or  turn 
to  go  down  into  the  soil,  thus  deforming  the  root,  or  a  new 
main  root  must  be  formed. 

The  aim  of  sprouting  the  seed  is  to  get  a  somewhat  earlier 
start  for  the  plant.  But  it  is  not  likely  that  an  early  start  of  the 
seed  at  room  temperature  helps  it  much  in  the  end  if  the  tender 
seedling  must  be  put  into  the  cold  soil  of  the  bed.  It  looks  more 
likely  that  the  plant  will  have  a  better  chance  if  the  seed  germin- 
ates at  somewhere  near  the  temperature  it  is  to  have  during  its 
early  growth. 

Certain  it  is  that  young  plants  taken  from  a  warm  to  a  cool 
place  are  set  back  in  growth  and  often  never  fully  recover. 

All  tobacco  growers  know  that  "hardening  off"  the  plants 
before  setting  has  to  be  done. very  carefully  to  avoid  injury. 

It  would  seem  that  vastly  more  injury  was  likely  when  seeds, 
sprouted  behind  a  kitchen  stove,  are  put  into  soil  with  a  temper- 
ature of  40°-50°  F.,  where  the  exquisitely  tender  root  fiber  must 
"harden  off"  before  it  grows  further. 

The  injury  is  not  considered  because  it  cannot  be  readily  seen. 

Even  if  we  grant  that  the  preliminary  sprouting  will  give  some 
earlier  plants  than  dry  seeding,  we  believe  it  is  done  at  the 
expense  of  the  general  thriftiness  of  the  bed,  and  that  to  get  the 
crop  set  in  the  field  very  early  is  rather  a  doubtful  advantage. 
Cold  storms  or  clear,^  very  cold  nights  are  likely  to  come  and 
set  back  the  growing  crop  if  it  does  not  kill  it. 


WATERING  TOBACCO  BEDS.  9 

Certain  it  is  that  the  crop  will  not  grow  in  such  cold  weather, 
and  when  it  starts  it  must  grow  continuously  and  fast  to  give  a 
crop  of  good  quality. 

We  urge,  therefore,  that  growers  make  a  comparison  them- 
selves next  spring,  sowing  sprouted  seed  and  dry  seed  at  the 
same  rate  in  different  parts  of  the  same  bed  and  noting  carefully 
the  dates  when  these  beds  respectively  are  ready  to  "pull"  and 
the  comparative  vigor  of  the  two. 

Watering  the  Beds.  A  very  successful  test  of  watering  the 
soil  from  below,  subirrigation,  was  also  carried  out  at 
Mr.  Ackley's. 

A  line  of  three-inch  glazed  tiHng  was  laid  from  three  to  five 
inches  deep  lengthwise  through  the  middle  of  the  bed.  The  line 
had  little  or  no  dip  and  at  one  end  came  above  the  surface  outside 
the  bed  with  an  elbow.  The  tile  for  90  square  yards  of  bed  cost 
about  $8.00.  Every  other  day  about  forty  gallons  of  water  were 
run  into  this  pipe  from  a  garden  hose.  No  other  watering  was 
done  except  on  the  surface  at  the  time  the  seed  was  sown. 

To  water  an  equal  area  of  bed  in  the  usual  way  while  the 
plants  were  growing  cost  $10.00  in  labor.  The  cost  of  subirri- 
gating  after  the  pipe  was  laid  was  inconsiderable,  say  ten 
minutes'  time  every  other  day. 

A  part  of  this  bed  was  sterilized  with  formalin.  Here  the 
plants  were  all  healthy.  There  was  some  disease  in  the  other 
part,  but  the  plants  grew  very  rapidly  when  not  diseased  and  fully 
as  well  as  in  the  bed  which  was  watered  on  the  surface  by  hand. 

Where  a  grower  has  several  beds,  we  urge  the  trial  of  this 
way  of  watering  on  a  single  bed.  If  it  is  as  successful  generally 
as  it  has  been  with  us,  it  will  save  labor  and  expense. 

The  Use  of  Tobacco  Water  on  Seed  Beds.  A  decoction  of 
tobacco  stems  is  sometimes  used  on  the  seedlings  as  a  fertilizer 
and  also  as  an  insecticide  and  destroyer  of  worms  in  the  soil. 
This  should  never  be  done.  Dr.  Clinton  of  this  Station  has 
proved  that  the  calico  disease  can  be  carried  in  the  stems  of 
leaves  infected  with  it,  and  that  tobacco  water  prepared  from  such 
stems  may  easily  infect  the  plants  which  are  watered  with  it.  He 
has  no  evidence  to  show  that  this  infection  passes  from  stems 
plowed  into  the  soil  to  the  young  plants.     He  has  been  only 


lO  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    IDD. 

able  to  induce  the  trouble  by  infection  through  the  leaf  or  the 
growing  part  of  the  stalk. 

Ventilation  of  the  Beds.  Proper  airing  of  the  beds  is  essen- 
tial to  protect  the  seedlings  from  "damping  off"  and  other 
fungous  diseases.  It  is  an  art  which  cannot  be  taught  except  by 
experience  with  the  bed  itself.  When  the  air  of  the  bed  is  nearly 
saturated  and  warm,  trouble  is  at  hand,  just  as  when  the  air  of 
the  barn  full  of  curing  tobacco  gets  into  the  same  state.  And 
the  remedy  is  the  same  in  both  cases,  viz.,  circulation  of  air  to 
carry  off  the  moisture,  even  if  this  causes  a  loss  of  heat  from  the 
soil,  the  bed  or  the  barn. 

"Calico."  The  experiments  of  the  Station  botanist,  Dr. 
Clinton,  so  far  indicate  that  most  of  the  "calico"  on  leaves  of 
commercial  value  in  the  field  traces  back  to  the  seed  bed  or  to 
infection  of  the  seedlings  at  the  time  of  transplanting.  To 
explain  this  more  clearly,  it  should  be  stated  that  "calico"  is  a 
disease  that  is  very  easily  transmitted  by  handling  a  healthy 
plant  after  handling  a  "calicoed"  plant,  especially  if  any  of  the 
juices  from  the  "calicoed"  plant  are  on  the  hands.  This  juice  is 
only  effective  on  the  immature  or  growing  leaves.  That  is,  one 
can  touch  with  it  a  fully  grown  leaf  at  the  base  of  a  tobacco 
plant  and  it  will  not  "calico,"  but  the  young  leaves  above  will 
become  "cahcoed"  though  not  even  touched  at  this  time.  From 
this  it  can  be  seen  that  if  there  are  any  "calicoed"  plants  in  the 
seed  bed  the  handling  of  these  while  transplanting  is  likely  to 
greatly  spread  the  "calico"  to  otherwise  healthy  plants.  This 
explains  why  sometimes  in  the  field  one  finds  every  other  plant 
"calicoed"  for  quite  a  distance  in  the  row.  The  man  who  set 
these  either  got  the  juice  from  a  "calicoed"  plant  on  his  hands 
or  else  got  a  bunch  of  plants  which  had  come  in  contact  with 
"calicoed"  plants,  while  the  man  who  set  the  alternate  sound 
plants  had  not  these  conditions. 

Unfortunately  "calico"  cannot  usually  be  recognized  in  the 
plants  while  in  the  seed  bed.  Occasionally  before  the  final  setting 
such  plants  are  found.  Whenever  they  are  found,  they  and  the 
surrounding  plants  should  be  pulled  out,  and  the  other  plants 
should  not  be  touched  until  the  hands  have  been  washed 
thoroughly  with  soap  and  water. 


CALICO  OF  TOBACCO.  II 

So  far,  the  only  known  methods  of  lessening  "caHco"  in  the 
seed  bed  are  avoiding  the  use  of  tobacco  water,  as  noted  before, 
and  the  probable  good  resulting  from  steam  sterilization.  Some 
growers  have  beheved  that  the  careless  use  of  fertiHzers  on  the 
growing  seedlings  produced  "calico,"  but  if  so,  this  has  not  yet 
been  proved  by  experimentation. 

The  subject  of  "calico"  will  be  further  discussed  in  the  forth- 
coming report  of  the  Station  botanist. 


SOIL    STERILIZER    READY    FOR    STEAMING. 


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